According to a new study led by researchers at the University of Michigan Comprehensive Cancer Center, when women, not their surgeons, have control over the type of surgery they receive, they are more likely to choose a more aggressive surgery that removes the entire breast, even though survival rates are the same for surgery that removes only the tumour.

“The current policy assumes that the high rate of mastectomy, the more invasive treatment, is a result of two things: providers not following guidelines that favour breast-conserving therapy and patients not being involved in the treatment decision. What we find is the opposite: Surgeons are strongly promoting lumpectomy, and most women say they were involved in the decision,” says lead study author Steven Katz, M.D., M.P.H., associate professor of general medicine at the U-M Medical School.

Katz and his team surveyed 1,844 women in the Los Angeles and Detroit metropolitan areas who had been recently diagnosed with breast cancer. The women were asked whether they made the surgical treatment decision, their doctor made the decision or they decided together. Patients were also asked whether their doctor had discussed mastectomy, breast-conserving therapy or both.

Additional questions were aimed at how much control the patient wanted to have over the decision process and whether she had any regret about her choice.

The researchers found that 27 percent of women who said they made the surgical decision received a mastectomy, compared to only 5.3 percent of women who said their surgeon made the decision, and 16.8 percent of women who said it was a shared decision.

Women who chose mastectomy were more likely to cite a fear of recurrence or fears about radiation treatment, which is necessary after lumpectomy.